1. Pressure Pressure Gradient Force Coriolis Force
Horizontal Winds
Pressure
Pressure Gradient Force
Coriolis Force

2. The Basic Pollution Problem
Transport
(wind vector and
turbulence)
Observed State
Source
(emissions)
Transformation
(chemical reaction)
Effects
Environment
Health
Environment
(temp, RH,rad, chems)

3. What causes the pressure to change
Is higher
50%
mass
level
Same mean Temperature
50%
mass
level
50%
mass
level
T in column 2 is greater
Column 1
Column 2

4. Horizontal Pressure Gradient Force (HPGF)
500 mb
496 mb
492 mb
~300km
isobar: line of constant pressure S W E

5. HPGF HPGF: due to the change in atmospheric pressure with distance.
Magnitude of HPGF: if p changes rapdily with horizontal distance--> isobars are closer together and HPGF is large
Effect of HPGF: air starts to move from H to L

6. Consider a hill Z distance
When height (z) changes fastest over the same relative distance, the slope of the hill is greatest

7. Suppose the hill is pressure
When the lines are closer together, the HPGF is greater!

8. Coriolis
The wind does not blow directly from H to L

9. The Wind does not blow directly from H to L
The Coriolis force causes an “apparent” deflection of the air to the right (left) in the Northern (Southern) Hemisphere

10. Geostrophic Wind

11. Gradient Wind

12. Winds near the surface